[13] The MARF Research and Development Group. The Modular Audio Recognition Framework and its Applications. [online], 2002–2012. http://marf.sf.net and http://arxiv.org/abs/0905.1235, last viewed April 2012.

[14] The Sphinx Group at Carnegie Mellon. The CMU Sphinx group open source speech recognition engines. [online], 2007–2012. http://cmusphinx.sourceforge.net.